The present invention pertains to processes for cleaning surfaces of material and more specifically to a process of cleaning semiconductor wafers.
In the most common prior art cleaning methods, wet chemistry is used in conjunction with sound (ultra sonic) energy, heat and/or fluid velocities to prepare the surface of semiconductor wafers and the like. This prior art does not provide, in all cases, adequate surface cleaning or preparation.
More recently, photonic energy has been introduced as a cleaner with additional benefits of surface reactions and simultaneous surface preparation. One of these photonic energy cleaning processes, known as photochemical, uses gas chemistries or liquids in vapor phase which require the condensing of the vapors on the target material to be done in a vacuum environment. An example of this type of cleaning is disclosed in U.S. Pat. No. 4,752,668, entitled xe2x80x9cSystem for Laser Removal of Excess Material From a Semiconductor Waferxe2x80x9d, issued Jun. 21, 1988, the laser portion of which is incorporated herein by reference. This severely limits the versatility and usefulness of the prior art processes and unduly complicates them. Another prior art photonic energy cleaning processes, known as photothermic, uses inert process gasses to clean the surface of semiconductors or displays. An example of this type of cleaning is disclosed in U.S. Pat. No. 5,643,472, entitled xe2x80x9cSelective Removal of Material by Irradiationxe2x80x9d, issued Jul. 1, 1997, the laser portion of which is incorporated herein by reference. Further, these prior art processes using lasers prohibit the use of reactive liquids and require high laser energies to provide particle removal.
Thus, it would be highly desirable to provide a cleaning process for surfaces of substrates, such as semiconductor wafers and the like, which is more efficient and versatile.
It is a purpose of the present invention to provide a new and improved laser cleaning process for substrates, such as semiconductors and the like.
It is another purpose of the present invention to provide a new and improved laser cleaning process for substrates, such as semiconductors and the like, which is highly versatile and efficient.
It is still another purpose of the present invention to provide a new and improved laser cleaning process for semiconductors and the like with the ability to simultaneously remove surface contaminants and prevent unwanted cleaning residues.
It is a further purpose of the present invention to provide a new and improved laser cleaning process for semiconductors and the like using liquid so that the generation of additional thermal reaction occurs at lower laser fluences.
It is still a further purpose of the present invention to provide a new and improved laser cleaning process for semiconductors and the like which enables the manufacturing of more complex structures with ultra clean semiconductor films without the negative impact of harsh chemicals to the material systems.
The above problems and others are at least partially solved and the above purposes and others are realized in a laser cleaning process for the surface of materials including the steps of providing a structure with a surface including thereon undesirable material to be removed, applying a wetting liquid to the surface of the structure, and irradiating the surface, using photon energy, with sufficient energy to remove the wetting liquid and the undesirable material. The wetting liquid can include reactive or non-reactive liquids and the irradiating step can be performed at atmospheric pressure.